5th / 6th Gear Grinding
 

This does't seem to be covered anywhere else, but I recently started having trouble with grinding mainly when going into 5th and 6th gears, mostly at higher speeds and after the car is running for a while. Also, occasionally, when downshifting into 1st I have severe grinding and have to engage in 2nd gear then go into first.

Couple questions:
Is this a normal sign of clutch wear? I've never had this type of trouble with other cars.

This started happening right after I changed over to Royal Purple 75W90. Could this have anything to do with it? I've checked the level so I don't think that's the issue.

What should I do? Take it to a dealer? Change back to normal tranny fluid?

Car is an 04, build around 10/03 with 47,000 miles.

Thanks for any help.

not likely that the rp oil had anything to do with it...

but i will ask, how did you check the level?? and who did the change??

this is one thing it could be.

http://www.finishlineperformance.com...4-06-1641a.pdf

beers :beer:

The Royal Purple fluid definitely changes the way the synchro behave in a very signficant way. On the OEM fill, I used to be able to double-clutch into 1st gear while in motion with a small blip. After switching to RP 75W90, I have to give it a HUGE blip (like overshoot by 2000 rpm over the actual shaft speed) to overcome the drag on the 1st gear synchro. The RP Gear Oil seems to be much thicker than the OEM stuff, and the effect is very obvious in the lower gears.

or not. unless your fill in canada is not the same as here. and which rp 75/90 did you use???

beers :beer:

I did the change, and I checked it by going back after about a week and trying to add more fluid until it just ran out of the fill hole, as the DIY said.

As for type, it is the Max Gear 75W90.

I'm going to search again to see what have been typical symptoms for normal wear & tear on the clutch.

Thanks

Umm I think there is only one RP.. Max-Gear 75W90.

I try to not use the synchro at all when downshifting, so I'm much more sensitive to how hard the synchros are working than people who don't double-clutch and just ram it into a lower gear without matching shaft speed first. Believe me, the RP definitely changed the way the synchro behave... for the better. But you can tell the fluid is thicker by the effort it takes to spin up the synchro on a downshift.

pm me if you want me to listen to it..

beers :beer:

Updated status
 

My car is now in the hands of Mazda. They're going to be rebuilding the transmission early next week. Diagnosed as Synchronizers gone bad.

did my angle work?

beers :beer:

They were really just really great for me. I didn't have to say much, they took it to the back, and about 30 minutes later came out and said they would need to keep it for a few days to rebuild it. I was pretty happy with that. They're going to let me know what the clutch looks like and if I should replace that now as well.

Are they covering the cost of the rebuild or is it coming out of your pocket. If so how much?

I have an 05 Rx-8 I just recently got my tranny fluid changed too and I developed a problem going in and out of fifth at high speeds as well. I drive it mostly highway so I don't make too many shifts, but just recently it started doing the same. Please let me know the outcome with Mazda so I know what I am up against.

Thanks

I've been having the 5th gear problem for some time. I often have to double clutch even on upshifts. It's really annoying. I have 90km on it now and a turbo so going back to the dealer isn't an option.

I can understand trannies having problems in the high-torque low gears, but grinding into 5th seems to indicate poor design or assembly.

I've had some hesitation on getting into 4th (before I went FI). I brought it to the dealer to have them inspect it before I had the turbo installed... and they said no issues found.

So now it's been about 13,000 miles since that time, and in the last week 4th gear has started to grind when I shift into it and rpm is >4,000 or so. If I go slowly, or rpms are lower, it has no issue. I'm shifting with the clutch to the floor and it still does it.

I had recently switched (less than 1k miles ago) diff and tranny fluids... it was rp before, and I wanted to just get new rp in there.

I don't think rp is to blame, but my situation is similar to some of the other posters.

I have about 2k left on my warranty. As I said, I reported issue with the transmission prior to the turbo, and now it's starting to act up. I don't know if it'll do me any good trying to talk to the local dealership.

See this thread for more on this issue:

https://www.rx8club.com/series-i-trouble-shooting-95/09-gt-5th-6th-gear-shift-grinds-158545/#post2785575

Cheers!